The present invention relates to the removal of a handler wafer from a semiconductor device wafer and, more particularly, relates to the addition of an amorphous carbon layer on the handler wafer which promotes efficient heating of the bonding layer between the handler wafer and semiconductor device layer to enable the separation of the handler wafer from the semiconductor device wafer.
Typical wafer-scale three dimensional (3D) integration involving chip-to-chip and chip-to-wafer bonding includes temporary bonding of a semiconductor device wafer to a handler wafer. The handler wafer may also be referred to as a carrier wafer.
In a typical process flow, semiconductor device wafers are bonded to an optically transparent handler wafer by use of an adhesive medium in order to facilitate the backside thinning of the semiconductor device wafer and then subsequent dicing and de-bonding of the handler wafer from the semiconductor device wafer.
Optically transparent wafers may be, for example, glass, quartz, sapphire. Optically transparent wafers have certain disadvantages in that they need to be engineered to have compatible coefficient of thermal expansion and ultraviolet light transparency with the silicon wafers that comprise most semiconductor device wafers. These optically transparent wafers further require separate wafer finishing fabrication facilities and tooling which makes them expensive.
The typical de-bonding process relies on optical/ultraviolet lasers for ablation of the bonding medium to enable release of the handler wafer from the semiconductor device wafer. Expensive optically transparent wafers must be used in this process which necessarily leads to higher costs.